On Tue, 12 Feb 2008 09:56:34 +0800, "Ystay"
wrote:

Maybe
you might try thoroughly cleaning and derusting the tanks before painting it
with a cementitious waterproofing compound. Essentially, it is cement and
latex. Very waterproof and it sticks like hell to almost everything
including metals. Available from builders shops and quite cheap.

You refer to Portland cement, I presume?

Casady